1. Technical Field
The present disclosure generally relates to light source devices that produce encoded visible light and light receiver devices that decode the encoded visible light, wherein a pattern encoded in the light is not generally visible to a human eye.
2. Description of the Related Art
Governments and private entities deploy and maintain individual lights and multi-light lighting systems. For example, street lights illuminate roads, sidewalks, and parking lots to provide visibility and safety. Crosswalk indicators let pedestrians know when it is safe to cross an intersection. Electronic traffic warning signs (e.g., “Road Closed,” “Do Not Enter,” and many others) are activated at various times of the day and night to inform and direct motorists and pedestrians. Airports, stadiums, private businesses, shopping establishments, and many other entities all rely on light sources for the safety and enjoyment of people. Maintaining the desired operation of light sources is important for safety, convenience, and energy efficiency.
In conventional lighting systems, a human observer is often used to verify the proper operation of individual light bulbs. That is, when a light bulb that is expected to be “on” fails to light and is instead “off,” a human being notices the failure. In some cases, people unaffiliated with the lighting system are relied on to detect failed bulbs. In one example, a city or other government agency often has a procedure whereby citizens are encouraged to report failing street lights. In other cases, employees are specifically tasked with detecting failed light bulbs. With large multi-light matrix billboard displays or scoreboards, for example, a maintenance employee may be tasked with ensuring that all or nearly all light bulbs are operating.
Some lighting systems use electronic circuits instead of human observers to detect failed light bulbs. In such cases, each light bulb fixture is typically configured with light detection or current detection circuits to detect the failure, and a wired or wireless radio or other transmission system to report the failure. When a failure is detected, the individual bulb or fixture sends an electronic message to a central controller that informs maintenance personnel of the failure. Self-reporting lighting systems are sometimes built into city lighting systems for energy saving purposes, but often, such systems are used in environments where light bulb failures can cause significant harm, such as airport runway and taxiway lighting, high-rise rooftop warning lights, and others.